A daily record, especially a personal record of events, experiences, and observations; a journal.(noun)
A book for use in keeping a personal record, as of experiences.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "diary" in a sentence
"Anna had underlined the word diary in her notebook."
"Between your excellent analysis in the VA -02 and your insights and ideas here, your diary is already “written.”"
"(Of course, if your diary is a Livejournal, it talks back to you in many voices ...)"